In Vitro Culture of Cotton Ovules

Abstract

In vitro culture of developing cotton ovules is a significant achievement in the continuing investigation of cotton and its agronomic properties. Pioneering work on in vitro growth of cotton ovules met with limited sucess, as ovule growth was abnormal and fiber development did not occur (Joshi 1960). Later, the effects of hormones, casein hydrolysate, and yeast extract on the development of the cotton embryo and integuments were reported (Joshi and Johri 1972). Beasley and coworkers began development of the cotton ovule culture system in 1971 (see Beasley 1977) in order to conduct investigations on fiber development. Eid et al. (1973) were successful in culturing 10-day postanthesis ovules on MS medium (Murashige and Skoog 1962), but the resulting embryos did not develop normally. Beasley and Ting (1973) subsequently developed a phytohormone-supplemented medium (BT) derived from the MS medium which supported the development of the ovules in a manner close to that observed in vivo. The BT medium could be utilized for both fertilized (Beasley and Ting 1973) and unfertilized (Beasley and Ting 1974) ovules. While this medium supported normal growth of the ovule and fiber during the first 2 weeks of development, the embryos did not continue to develop normally, and subsequently degenerated. Stewart and Hsu (1977) resolved this problem by inclusion of an ammonium ion amendment to the medium; by making this medium modification, 50% of the ovules produced physiologically mature embryos.